The System Dynamics model development process is summarised in the schematic diagram of a model life cycle in Figure 3. The modeling process starts with defining the purpose/goal of the system. Then boundaries of the system to be modelled are specified. This is followed by identification of key variables in the system that affects the system, the most. Then behaviour of the key variable is described, the stocks and flows are identified, and their structure is mapped in the modeling tool using basic building blocks. Quantitative information, i.e., equations and data, is included in the model structure. The model is run to test the behaviour. The model is then evaluated and adjustments are made. Once the model is replicating system behaviour, it is ready for simulationmodeling.
The energy recovery system in a parallel hybrid electric vehicle (HEV) is an important component to recycle and store the excess kinetic energy and potential energy during the braking, downhill, idling etc conditions, aim to make full use of the electrical energy, and effectively improve the HEV's fuel economy[1, 2]. However, the energy recovery system generally produce additional forces to the vehicle during recycling kinetic energy or potential energy, which will change the original braking allocation of the vehicle, thus affected the vehicle power composition and stability [3-5]. Therefore, it is necessary to build a proper model of the parallel HEV for studying the control strategy of the vehicle stability during effectively energy recovery process. CarSim, as a vehicle multi-body dynamics software, is widely used for the prediction and simulation of the vehicle stability and fuel economy performance characteristics, and has a friendly interface with Simulink software to jointly build an external module of vehicle system, which makes the modeling more flexible[6, 7].
In summary, we perform MD modeling and simulation to elucidate the underlying mechanisms of cerium under the ultra-precision diamond cutting. The EAM and Morse potentials are respectively employed to describe atomic interactions within cerium workpiece and the in- teractions between cerium workpiece and diamond cut- ting tool. The elastic constants, mechanical properties, and propensity of phase transformation of cerium phases are evaluated, which demonstrates the feasibility of pre- dicting phase transformation of cerium by the current established MD model. Subsequent MD simulations of diamond cutting reveal that the plastic deformation of cerium is governed by dislocation nucleation and subse- quent glide, which is similar with other fcc metals. In addition, there is γ ➔ δ phase transformation occurred within both machined surface and formed chip. It is found that high quality of machined surface and low ma- chining force can be achieved in the diamond cutting of cerium with the optimal machining conditions, i.e., a rake angle of 30° for a crystal orientation of (010).
The growing number of obese individuals in most industrialized countries has be- come an important social issue. Motor vehicle crashes (MVCs) are the leading cause of injury, yet the role of obesity (either cushion or momentum effect) on MVC injuries is still unknown. The objective of this study is to elucidate the effect of obesity on body in- juries in MVCs through computational modeling and simulation. MADYMO, a mathe- matical dynamic simulation code, is used for model simulation of a vehicle frontal impact with airbag systems, seatbelts and simplified vehicle interior components. Male and fe- male obese dummy models (body mass index greater than 30) are developed based on the MADYMO Hybrid III 50 th percentile male and 5 th percentile female model, respectively. To represent subcutaneous fat geometry and properties, finite element models were created based on the geometry data reconstructed from MRI datasets of obese subjects. The fat model with Mooney-Rivlin hyperelastic properties is integrated into the standard dummy models. Four injury criteria on head, neck, thorax and lower extremity are as- sessed against various settings of deceleration pulses and occupant restraint systems. From the simulation results, obese males have a much higher risk of injury (especially head and thorax) than standard males, while obese females have slightly increased risk of head and thorax injury. The results are consistent with the findings from real world crash data in literature.
Owing to the importance of the saliva protein D7r1 of Anopheles gambiae as an anti-malarial target, the present study reports the in silico structural analysis that providing insights into its structural architecture. In silico analysis has reached to such advancement that results obtained from computational study are much more reliable and comparable to experimental results. The three dimensional structure of D7r1 has been predicted through homology modeling which shows structural similarity to its experimentally determined template structure (PDB ID: 2PQL). Similarly, the predicted D7r1 also contains eight helices connected by several loops which resemble the structural architecture of D7r4. At present, the molecular dynamicssimulation study proven to be an essential step in computational biology which provides insight into protein structural stability through RMSD and RMSF plot. In our study, to explore the conformational flexibility and structural transition occur in D7r1, essential dynamics were employed which shows that three cluster basin at different time interval. Accordingly, FEL representative structures at different conformational state were retrieved and validated through Ramachandran plot. Further, similar to D7r4, same active site residues involved in binding pocket formation and opened a gateway to investigate the interacting mechanism of D7r1 with its suitable ligands and protein interacting partners through molecular docking study. Since, the structural knowledge of macromolecule is an important pre-requisite to understand its functional role. Hence, the predicted D7r1 structure and its active site might be useful in further attempts to elucidate the experimental structures as well as to design new lead molecules acting on novel drug targets considered as a suitable starting point for structure based drug design in the treatment of malaria.
Abstract: This paper describes the use of FlightGear, an open-source flight simulator, and JSBSim, an open source flight dynamics model, to model and simulate a small autonomous Unmanned Aerial Vehicle (UAV). A small commercial electric engine Cessna-182 radio controlled (RC) aircraft was chosen to represent the UAV. The first step was to create the required JSBSim aircraft configuration files by using the Aeromatic v0.8, a free web application to create aircraft configuration files for use with the JSBSim. The next step was to make educated guesses to refine important sections in the created configuration files with the assistance of available data of similar UAV. In order to perform a visual simulation, a 3D model for the Cessna-182 (RC) was created using AC3D, a commercial 3D modeling software tool. To fly the modeled UAV autonomously a tuning process was made for the built-in generic PID (proportional, integral, and derivative) autopilot of FlightGear, which has the ability to hold aircraft velocity, vertical aircraft speed, altitude, pitch angle, angle of attack, bank angle, and true heading. Finally, a flight path, which contains a number of waypoints chosen over a selected area using Google Earth map, was constructed. In order to use the chosen waypoints with FlightGear navigation system, a unique ID was assigned to each waypoint, and the FlightGear database was altered to include the new waypoints with their IDs. The outcome of the paper was a complete JSBSim flight dynamic model for the Cessna-182 (RC), with 3D model for visual simulation and an effective autopilot. A good autonomous flight simulation was performed. This paper concluded that modeling and simulating a UAV accurately is not an easy task, due to the need to calculate many parameters either by physical measurements, experiments, or estimation from available data of similar UAV, or by software tools.
Abstract: This paper deals with the modeling and simulation study of Commensal-host species system together with the inclusion of parasite population. The model comprises of three populations viz. Host, Commensal and Parasite. The Commensal population gets benefit from Host population but the former do not do any harm to the latter. The parasite population gets benefit and also do harm to Host population. However, the Commensal population only harms the parasites. The mathematical model is comprised of a system of three first order non-linear ordinary differential equations. Mathematical analysis of the model is conducted. Positivity and boundedness of the solution have been verified and thus shown that the model is physically meaningful and biologically acceptable. Scaled model is constructed so as to reduce the number of model parameters. Equilibrium points of the model are identified and stability analysis is conducted. Simulation study is conducted in order to support the mathematical analysis. In the present model the Commensal population lies higher and the parasite population lies below respectively the host population. This fact is well supported by the mathematical analysis as well as simulation study. The results of analysis and simulation are presented and discussed lucidly in the text of the paper.
With increasing concern over the environment and ever stringent emissions regulations, the electric vehicle has been investigated as an alternative form of transportation. However, the electric vehicle suffers from relatively short range and long charging times and consequently has not become an acceptable solution to the automotive consumer. The addition of an internal combustion engine to extend the range of the electric vehicle is one method of exploiting the high efficiency and lack of emissions of the electric vehicle while retaining the range and convenient refueling times of a conventional gasoline powered vehicle. The term that describes this type of vehicle is a hybrid electric vehicle. Many configurations of hybrid electric vehicles have been designed and implemented, namely the series, parallel and power-split configurations. This paper discusses the modeling and simulation of split plug-in hybrid electric vehicles. Modeling methods such as physics-based Resistive Companion Form technique and Bond Graph method are presented with powertrain component and system modeling examples. The modeling and simulation capability of existing tools such as ADvanced VehIcle SimulatOR (ADVISOR) is demonstrated through application examples. Since power electronics is indispensable in hybrid vehicles, the issue of numerical oscillations in dynamic simulations involving power electronics is briefly addressed.
Abstract: Unmanned Aerial Underwater Vehicles (UAUVs) with multiple propellers can operate in two distinct mediums, air and underwater, and the system modeling of the autonomous vehicles is a key issue to adapt to these different external environments. In this paper, only a single set of aerial rotors with switching propulsion abilities are designed as driving components, and then a compound multi-model method is investigated to achieve good performance of the cross-medium motion. Furthermore, some additional variables, such as water resistance, buoyancy and their corresponding moments are considered for the underwater case. In particular, a critical coefficient for air-to-water switching is presented to express these gradually changing additional variables in the cross-medium motion process. Finally, the sliding mode control method is used to reduce the altitude error and attitude error of the vehicles with external environmental disturbances. The proposed scheme is tested and the model is verified on the simulation platform.
Alhamdulillah, all praises to Allah for the strengths and His blessing in completing this thesis. Special appreciation goes to my supervisor, Mr. Fauzi bin Ahmad, for his supervision and constant support. His invaluable help of constructive comments and suggestions throughout the modeling, simulation, controlling and thesis works have contributed to the success of this research.
Vertical dynamicsmodeling and simulation of a six-wheel unmanned military vehicle (MULE) studied in this paper. The Common Mobility Platform (CMP) chassis provided mobility, built around an advanced propulsion and articulated suspension system gave the vehicle ability to negotiate complex terrain, obstacles, and gaps that a dismounted squad would encounter. Aiming at modeling of vehicle vertical dynamics, basic and geometrical parameters defined and degrees-of-freedom specified on a compromise between accuracy and complexity of two models. Equations of motion provided on two linear and nonlinear 5-degree-of- freedom models using two different modeling methods. There is good agreement between time responses of two presented models. The main differences of two models observed in articulated suspension degrees-of- freedom while the vehicle subjected to high frequency maneuvers that cause severe oscillations on wheels and arms in comparison to vehicle body due to lower mass and inertia properties. The linear model can be used to design a controller and the nonlinear to predict vehicle motion more accurately. Sensitivity analysis of the influential parameters is also presented to specify effects of different parameters. Results of this study may be used to design articulated suspension and making next frequency analyses.
HeredN dt ⁄ 0 and . In the compartment model the population is assumed to be closed. That is, births, deaths and migrations are considered to be negligible and omitted. Thus, the population size parameter is a constant. Here represents the number of individuals those are susceptible to the disease but not infected at time. The parameter denotes the number of individuals those are exposed to the virus or infected but not yet tested positive of the infection. The parameter denotes the number of infected individuals who are able to spread the disease to other susceptible people, and represents the number of individuals those have successfully gained immunity from the disease die or removed by death. After exposed by the virus the individuals from the susceptible compartment enters the exposed compartment before they become infectious individuals and later either recover or die. The parameter represents the transmission rate of disease from susceptible to exposed, is rate at which an infected individual becomes infectious per unit time. Similarly, 1⁄ and 1⁄ are the average durations of incubation and infectiousness periods respectively. 2.2. Assumptions of the Model In this study , Susceptible, Exposed, Infected, Recovered, epidemic model have been considered and classified the infected population I as those first stage or catarrh I and second stage or eruption I . A simulation study will also be conducted by assigning different valid values to the parameters of the model. The present model has a compartmental structure and is designed based on the assumptions described as follows: a. Assume that the susceptible people are recruited from the total population at a constant rateΛ. b. The population is homogeneously mixing and reflects increasing
Most of related research is focused on pedestrian safety protection of frontal crash between pedestrian and vehicle [8, 9]. However, since the Chinese invented the electric bicycles in 1996 which are categorized as non-motor vehicles and usually run at a speed of 35 km/h or even higher, China has been the largest pro- ducer and consumer of the electric bikes. Owing to high speed of the electric bicycles, there are often some hidden accidents, such as “door of the car opened resulting to death” (as shown in Fig. 1). The collision accident between the driver of non-motor vehicle and
. “Flow Analysis of Rocket Nozzle Using Computational Fluid Dynamics (CFD)” . K.M. PANDEY , Member IACSIT and A.P. Singh , International Journal of Chemical Engineering and Applications, Vol. 1, No. 2, August 2010 ISSN: 2010- 0221 “CFD Analysis of Conical Nozzle for Mach 3 at Various Angles of Divergence with Fluent Software” . A.A. Khan and T.R Shem Bharkar, “Viscous Flow Analysis In A Convergent Divergent Nozzle” proceeding of the international conference on aerospace science and Technology, Bangalore, India, June 26-28,2008.
To achieve the objective of the Transport Integrated High- way Security system (THIS), the coordinates from the GPS has to be able to identify accurate position of incident. Therefore Kalman filter is introduce into the vehicle unit to enable filtration of the system noise. This will help the vehicle unit to send accurate locations. To achieve this, different iterations are performed to give the best means of using Kalman filter. Various parameters are varied to suit the vehicle system. When the Kalman filter is connected to the output of the vehicle unit system it should be able to transmit information depending on:
Chapter 4. Signal Analysis 31 crash pulse and the car kinematics that include the velocity and dynamic crush. The velocity and the displacement of the vehicle impact is obtained by integrating the approximated crash pulse. One of the facts to be considered here is that the experimental setup was for a front impact and the most relevant graph was the one in X direction, however the accelerometers recorded some crash pulse in Y and Z directions that needs to be taken into account. The acceleration data was input into the Curve Fitting Toolbox and Gaussian approximation was used as it is shown in Figure 4.6 and polynomial function curve fitting is used for comparison which is shown in Figure 4.7. These graphs show the accelerations, velocities and dynamic crushes of the vehicle during the impact in the X-axis direction(all the graphs are of high resolution, for a better view, zoom to see the specified area of target). It can be seen in both figures that the initial velocity is not equal to 35km/h as stated in the experiment description. The speed shows to be about 3km/h higher. This discrepancy is a result of using raw data - without filtering. On the same graphs the maximum dynamic crush and the time of occurrence are also shown. At time zero the front panel of the car was in contact with the rigid obstacle at 35 km/h. The velocity of the car decrease rapidly and the displacement viewed from the X-axis increased. The maximum dynamic crush happens at the point where the decreasing velocity of the vehicle reaches zero value from the initial velocity. The vehicle is shown to have maximum dynamic crush of 59.11 cm. The maximum dynamic crush occurred at time of 86.11 ms. After the maximum crush occurrence the car started to slowly rebound.
When the vehicle moves underwater at high speed, the low pressure of the vehicle surface causes the liquid water changing to the gaseous state, thus producing cavity. With the increase of speed, the resulting cavity becomes larger and larger. Eventually, the large supercavity connected together. This is the so-called cavitation phenomenon. Supercavitating torpedo and supercavitating projectile are common supercavitating vehicles . Researchers have carried out a lot of studies on cavitation morphology and control technology of supercavitating vehicle [2-4]. But there is few studies on radiated noise of supercavitating vehicle . In fact, studying and mastering the radiated noise characteristics of underwater supercavitating vehicle is of great importance for underwater acoustic homing, detection and stealth. In this paper, the supercavity form on the vehicle stern is simplified as bubble cluster. Based on the single cavitation bubble collapse noise model and the statistical characteristics of the bubble cluster, the cavitation noise waveform and spectrum characteristics of supercavitating vehicle were simulated and analyzed.
Field testing using full scale vehicle to evaluate the vehicle dynamic behavior has some drawbacks especially endangering the test driver. It is very dangerous to the driver to test full scale vehicle especially when it is required to push the vehicle to its limits to observe what happens in non-linear regions of vehicle behavior (Yih, 2000). The cost to develop full scale vehicle and maintenance cost are relatively high. Furthermore, modification of vehicle parameters requires a lot of time and this limit the repeatability of the test.
Due to the great load ability, big traction and the small unit area pressure, the tracked vehicle is always regarded as the army’s important combat equipment. With the needs of heavy-motorized modern warfare, tracked vehi- cle must be adapted to a variety of complex and harsh terrain to have a stronger ability to survive in future wars . However, because the traditional model of tracked vehicle was based on empirical formula and a large number of tests with lengthy development cycle, tracked vehicle developed very slowly. Especially when driving high-speed in the irregular terrain, the running gear of the tracked vehicle is likely to fracture due to the uneven fore of the track. When the vehicle turns, due to the lack of grip, it is likely to cause skidding, even in the side turn [2,3]. In this paper, combined with the practical issues of a surface adaptive mechanism for tracked vehicle, based on virtual manufacturing technology, the 3D simulation model of the tracked vehicle is established through the multi-body software RecurDyn to simulate its adaptive ability .